ABSTRACT We investigated the photovoltaic and piezoelectric power generation characteristics of ferroelectric poly(vinylidene fluoride‐ran‐trifluoroethylene, PVDF‐TrFE) thin films on flexible indium tin oxide (ITO)/polyethylene terephthalate (PET) substrates. The solar cells and piezoelectric hybrid devices provide consistent energy to extend battery life and improve self‐charging. The flexible PVDF‐TrFE thin films with a transmittance of about 60% in the visible region showed a remanent polarization of about 10.5 μC/cm 2 (2P r ~ 21.0 μC/cm 2 ) with excellent β‐phase formation. The flexible PVDF‐TrFE thin films exhibited optimal ferroelectric and piezoelectric properties by exhibiting β‐phase without α‐phase. Since β‐phase is the phase that carries high dipole alignment of the material, which is important for maximizing power output, the performance of the material in photovoltaic and piezoelectric applications is enhanced. The PVDF‐TrFE capacitor exhibited not only a piezoelectric generation characteristic with an approximate voltage of 1.1 V under compression, but also a photovoltaic generation feature with an open‐circuit voltage of about 0.23 V and a short‐circuit current of approximately 0.13 mA/cm 2 .
We investigated the role of surface charges in writing and reading ferroelectric bits on an epitaxial PbZr0.48Ti0.52O3 thin film by electric force microscopy (EFM). The sign of EFM surface potential was reversed within several hundred microseconds for 10 V. For a negative bias voltage of −10 V, EFM surface potential was reversed in several milliseconds. The different time scales of the EFM surface potential reversals originate from the screening of the ferroelectric polarization charges by the surface charges which pass over two different Schottky barriers depending on the applied bias polarity.
We fabricated high quality epitaxial BiAlO3 thin films that exhibited a relatively high c∕a ratio of about 1.05 with a pseudotetragonal structure. On the atomic force microscope morphology of the BiAlO3 thin film, we observed large terraces with a width of about 1000Å and terrace heights of nearly the same to one lattice constant. This indicates that the BiAlO3 thin film has an ideal layer-by-layer growth mode. The BiAlO3 thin film also showed a good ferroelectric property with a high remanent polarization of about 29μC∕cm2.
We investigated the canonical ferroelectric response of a thin ferroelectric polymer film using a piezoelectric force microscopy method. The thin ferroelectric poly(vinyliden fluoride-ran-trifluoroethylene) layer with a thickness of was prepared on a (111) substrate by a Langmuir–Blodgett method. The flip speed into upward polarization in the thin ferroelectric polymer layer is faster than that into downward polarization because the adhesion strength of the fluorine atoms in the ferroelectric polymer layer with the Pt electrode is stronger than that of the hydrogen atoms.
Abstract A novel fabrication method of Co and Ni metal nanorods (NRs) without catalyst or template, based on the spontaneous formation of NRs during plasma‐enhanced atomic layer deposition (PE‐ALD) is developed. Pure Co and Ni NRs 9–10 nm in diameter are synthesized on SiO 2 and Si substrates by using metal–organic precursors and an NH 3 plasma mixed with a suitable amount of SiH 4 as a reactant. The lengths of the NRs are controlled on the nanometer scale by changing the number of PE‐ALD growth cycles. Superconducting quantum interference device magnetometer measurements confirm the magnetic anisotropy of Co NRs caused by shape anisotropy.
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